2+1 road

A 2+1 road is a specific category of three-lane road, common in Sweden, Finland, Ireland, and other European countries. It features two lanes in one direction and one lane in the other, alternating every few kilometers, and often separated by a median barrier, typically a cable barrier or concrete barrier. The design aims to provide overtaking opportunities while maintaining safety by reducing head-on collisions. The two lanes in one direction are intended to allow for safer passing of slower vehicles without entering the opposing lane of traffic.

The lane arrangement alternates periodically between 2+1 and 1+2, allowing traffic in each direction to benefit from the two-lane configuration at different points along the road. This alternating pattern is crucial to the functionality and safety of the road.

The median barrier is a key component, preventing vehicles from crossing into the opposing lane, which is a major cause of serious accidents on undivided highways. This barrier effectively eliminates head-on collisions, significantly improving road safety.

2+1 roads represent a compromise between a standard two-lane road and a four-lane divided highway. They are often implemented in areas where traffic volume doesn't justify the expense of a full four-lane highway but warrants improvements over a basic two-lane road. They offer enhanced safety and capacity at a lower cost than a four-lane divided highway.